By using sound waves to push and pull matter like science fiction tractor beams, scientists have developed "acoustic tweezers" that can manipulate blood cells and microscopic worms on a platform the size of a dime.

The dexterous control this device could give researchers tinkering with organisms in microchip-sized laboratories could potentially lead to a wide range of medical insights, the inventors proposed.

Scientists are miniaturizing beakers, eyedroppers and other scientific implements to fit in labs-on-chips with the aim of running thousands of experiments at the same time, which could help find life-saving cures more quickly. Researchers would like to grasp items within such miniature labs with as much dexterity as they have in their hands, and to a certain extent they can do so with so-called "optical tweezers," which use laser beams to hold and move objects.

The problem with optical tweezers is that lasers can burn organisms, and in any case are expensive, bulky and difficult to operate. Alternatives to optical tweezers each have their own drawbacks as well -- for instance, magnetic tweezers require targets covered in magnetic materials, which can damage cells.

Now scientists reveal acoustic tweezers can use sound waves to control items regardless of their optical, electrical or magnetic properties, making them more versatile than their counterparts.

"The manipulation is achieved in a touchless way, like being controlled by a virtual hand," said researcher Tony Jun Huang, a bioengineer at Pennsylvania State University.

The acoustic waves are generated using electrodes made of gold that resemble combs with tines 25-50 micrometers -- or millionths of a meter -- wide. These were deposited on crystals of lithium niobate, a material that converts electricity into vibrations. The design of the electrodes enables them to produce a range of sound frequencies with the crystals.

A miniaturized ultrasonic device capable of capturing and moving single cells and tiny living creatures is compared to a U.S. dime. (Photo Credit: Xiaoyun Ding, Stephen J. Benkovic, and Tony Jun Huang - Penn State)

The sound generators were positioned around a square chip of silicone rubber measuring 2.5 millimeters on each side. By carefully tuning what frequencies they used, the scientists could force items around within the area where the acoustic waves overlapped.

In experiments, the researchers could move micrometer- to millimeter-scale objects, including plastic beads, cow blood cells, and even whole animals, such as the millimeter-long worm Caenorhabditis elegans -- trapping it still, moving it to and fro, and even stretching it out.

"It totally blew me away that they could trap a whole organism like C. elegans," said biomedical engineer Eric Pei-Yu Chiou at the University of California, Los Angeles, who did not take part in this research. "I don't see any other technology able of doing that in such a biocompatible way."

Compared with optical tweezers, acoustic tweezers can get integrated onto chips without any expensive and bulky laser or optical components. They can also in principle manipulate up to tens of thousands of objects simultaneously, a challenging task for optical tweezers. In addition, they are significantly safer to live organisms because the power density brought to bear on targets is 10 million times lower.

"The acoustic tweezers are as noninvasive as many low-power ultrasonic technologies," Huang said. He added that ultrasound imaging, used on pregnant women, is one example.

Acoustic tweezers could help researchers see how cells respond to changing environments by moving them from one setting to another, and the ability to see how cells change and respond to physical pressure could also shed light on the activity of vital tissues such as heart muscle and blood vessels.

"This could, for instance, help show how cells respond to a series of pharmaceutical treatments, or to pulses of a drug as opposed to a continuous gradient," said researcher Stephen Benkovic, a biochemist at Pennsylvania State University. "We could learn more about high blood pressure or muscles under tension this way.".

One advantage that optical tweezers have is that they are currently capable of controlling smaller items than acoustic tweezers, down to a few nanometers or billionths of a meter in size. The researchers expect they might be able to reach such fine levels of manipulation with acoustic tweezers by using higher-frequency acoustic waves, "although we have to be very careful, since higher frequencies could damage cells," Huang said.

Related Stories

(PhysOrg.com) -- Manipulating tiny objects like single cells or nanosized beads often requires relatively large, unwieldy equipment, but now a system that uses sound as a tiny tweezers can be small enough to place on a chip, ...

In efforts that can improve studies of biological objects and the construction of nanotech materials, researchers at the University of California-Berkeley have invented "optoelectronic tweezers," a new way of controlling ...

(PhysOrg.com) -- Cutting-edge “tweezers” are so sensitive that they can feel the tell-tale tug of tiny concentrations of pathogens in blood samples, yet don’t ever need to be sterilized—or even held—as they are ...

The ability to sort cells or manipulate microscopic particles could soon be in the hands of small laboratories, high schools and amateur scientists, thanks to researchers at the University of Pennsylvania School of Engineering ...

Wok tossing is essential for making a good fried rice—or so claim a group of researchers presenting new work at the American Physical Society's Division of Fluid Dynamics 71st Annual Meeting, which will take place Nov. ...

One-fifth of global electricity consumption is based on lighting; efficient and stable white-light emission with single materials is ideal for applications. Photon emission that covers the entire visible spectrum is, however, ...

Soot belches out of diesel engines, rises from wood- and dung-burning cookstoves and shoots out of oil refinery stacks. According to recent research, air pollution, including soot, is linked to heart disease, some cancers ...

Microscopes make the invisible visible. And compared to conventional light microscopes, transmission x-ray microscopes (TXM) can see into samples with much higher resolution, revealing extraordinary details. Researchers across ...

When Konrad Rykaczewski moved to Arizona's Sonora Desert region six years ago he took a water bottle and sprayed the plants in his front yard, not to water them, but to see how they interacted with water droplets.